We propose to isolate and identify the toxins produced by algae of both marine and freshwater environments. These toxins are hazardous to humans directly or following ingestion of the toxins by animals commonly used as human food resources. As a result, these food resources are denied for human consumption or if unknowingly used, can cause severe discomfort, acute toxicity, or even death. Culture techniques have been developed at Brookhaven for growing microalgae on a large scale. Environmental conditions for maximal algal growth will be determined to assure sufficient material for continuous chemical investigation. The effects of environmental factors on toxin production will be investigated. In those frequent instances where several toxins are produced by an algae, the biosynthetic mechanisms influencing the relative amounts of the toxins will be examined. Comparisons will be made between toxic and non-toxic strains of selected algal species. Knowledge derived from these studies will be useful for developing methods to decrease or eliminate toxin production or toxic algal growth. The algal toxins will be isolated and characterized as pure chemical compounds at Berkeley. They will be subjected to structural investigations and synthesis. Knowledge gained in these studies will be applied to devising sensitive chemical assays for the toxins. At present, bioassays are available for some toxins but they are commonly insensitive and troublesome to apply. Sensitive chemical assays will permit rapid and frequent environmental monitoring, thus providing a greater safety factor for the utilization of marine food resources when warranted. The chemical studies will allow for the possibility of devising antidotes, for studying the mechanism of toxic action, and will provide clues for influencing toxin biosynthesis. The availability of pure toxins from these studies has potential pharmacological value. The most effective way to attack this overall problem is by a collaborative effort to exploit the expertise of the Berkeley and Brookhaven laboratories. Frequent exchange of staff between the two laboratories is anticipated.